geier



Jan. 31, 1956 L. w. GEIER 2,733,381

MAGNETRON TUNING STRUCTURES Filed Aug. 28, 1952 2 Sheets-Sheet l 4 i .s2 5 2 JL 27 Z 2/ I a awe/won LEONAQD W. 695/; BY 61% W 3 ATTORNEY Jan.3], 1956 w, GE|ER MAGNETRON TUNING STRUCTURES 2 Sheets-Sheet 2 Filed 4m28, 1952 q A)? g p w mm vm e o .WGQOW WW A my 2,733,381 MAGNETRON TUNINGSTRUCTURES Application August 28,1952, Serial No. 306,873 Claims.(Cl..31539.61)

This invention relates to electron discharge devices of the magnetrontype and, more particularly, to tuning structures used for varying theoperating frequency of said devices.

In conventional magnetron tuning structures, the support members onwhich the tuner is mounted pass through apertures in the upper magneticpole piece and are rigidly attached to a movable member above the polepiece which is hermetically sealed by a flexible seal, such as abellows, to the remainder of the envelope of the device. It has beenfound that high frequency energy present in the magnetron .cavities willfeed through the apertures surrounding the tuner support members invarious regions of the tuning range and will excite resonances atfrequencies determined by the geometry of tuner support structureswhich, in many cases, are so close to the operating frequency of themagnetron as to cause serious interference therewith.

This invention discloses that the energy may be substantially preventedfrom passing through the apertures in the pole piece, through which thetuning support members pass, by positioning resilient shorting membersaround the tuner support members in the apertures in the pole piece suchthat said resilient members substantially contact both the supportmembers and the pole piece.

Specifically, it has been found that the resilient members may comprisetoroidal springs of tungsten or any other resilient conductive materialwhich will withstand elevated temperatures.

Other and further objects and advantages of this invention will beapparent as the description thereof progresses, reference being had tothe accompanying drawings wherein:

Fig. 1 illustrates a longitudinal cross-sectional view of a magnetronembodying this invention;

Fig. 2 illustrates a transverse cross-sectional view of the device shownin Fig. 1 taken along lines 22 of Fig. 1; and

Fig. 3 illustrates a partial longitudinal cross-sectional view of asecond embodiment of the invention.

Referring now to Figs. 1 and 2, there is shown a magnetron dischargedevice comprising an anode structure having an anode ring 11. Extendinginwardly from the inside of anode ring 11 are anode members 12 which arealternately connected, at their upper and lower edges near their innerends, by conductive straps 13, according to well-known practice. Acathode structure 14, of conventional type, is positioned in the spacedefined by the inner ends of anode members 12 and is supported by asupport structure 15, which extends down through an aperture in thelower magnetic pole piece 16 of the magnetron, which is hermeticallysealed to anode ring 11. Support member 15 is hermetically sealed tomagnetic pole piece 16 by means of an insulating seal, not shown. Thestructure disclosed thus far is conventional, and any desired magnetronanode and cathode configuration may be used.

United es Presto Extending downwardly into the cavities, defined by eachpair of adjacent anode members, is a plurality of tuning elements 17.The tuning elements 17, as shown here by way of example, extend into thecavities in the inductive regions thereof adjacent the anode ring 11 andaccordingly tune the cavities substantially entirely by eddy currenttuning. However, the tuning elements may extend into the cavitiesadjacent their inner ends to tune the cavities capacitively or acombination of inductive and. capacitative tuning elements could beused. Tuning elements 17 are attached to a support ring 18 above theanodemembers 12. The support ring 18 in turn is rigidly attached to aplurality of support members or rods 19 which extend upwardly throughapertures 20 in the upper magnetic pole piece 21 of the magnetron whichis hermetically sealed to the anode ring 11. Support members 19, whichmay be, for example, solid metallic rods, after passing through upperpole piece 21 are embedded in a guide member 22, which is slidablymounted in a cylinder 23, cylinder 23 in turn being rigidly attachedthrough a flanged member 24 to a cylindrical case member 25 surroundingcylinder 23 and hermetically sealed to upper magnetic pole piece 21. Aflexible her- Inetic seal is provided between the movable guide member22 and the flanged member 24 by means of a bellows 26, surroundingcylinder 23.

In order to prevent energy in the magnetron anode structure from feedingthrough the apertures 20, through which the support members or rods 19pass, there are provided toroidal springs 27 surrounding each of thesupport members 19. The toroidal springs are positioned in recesses inthe magnetic pole piece cut down from the upper surface thereofsurrounding the apertures 20. The springs 27 are held in place byretaining cylinders 28, which are pushed into the recesses containingthe springs 27 above the springs 27. In order to insure a resilientcontact between the members 19 and the springs 27, the inner diameter ofthe springs 27 in their normal position is somewhat smaller than thediameter of the members 19. Since the coils 27 produce an electricalshort between the support members 19 and the upper magnetic pole piece21, energy is prevented from passing through pole piece 21 and henceundesirable resonances which might occur from the dimensions of thespace surrounding the bellows 26 are prevented from interfering with theoperation of the magnetron.

Referring now to Fig. 3, there is shown another embodiment of thisinvention. Fig. 3 discloses an anode structure 10 similar to that shownin Figs. 1 and 2. However, instead of having the tuning elements 17 ofFigs. 1 and 2 attached to a support ring, the tuning elements in Fig. 3are part of the support rods as indicated at 29. Each of the rods 29 hasa toroidal coil 30 surrounding it in resilient contact therewith as itpasses through the pole piece 21. The coils 30 are similar to the coils27 shown in Figs. 1 and 2 and are held in place by similar retainingcylinders 31. By positioning the distance of the coils 30 suflicientlyfar above the anode members 12, the resonance produced by the electricalcircuit comprising adjacent tuner elements may be adjusted to anydesired frequency remote from the operating frequency of the device,thereby eliminating interference from tuner resonances. In addition,resonances which might occur in the region above the upper pole piece 21are prevented from being coupled through the apertures in pole piece 21through which the rods 29 pass, thereby preventing their interferencewith the operation of the device.

This completes the description of the embodiments of the inventionillustrated herein. However, it is to be clearly understood that manymodifications thereof will be apparent to persons skilled withoutdeparting from the spirit and scope of this invention. For example, the

resilient contacting member could be used in slidable shorting devicesother than magnetron tuners and the slidable tuner with the shortingmember could be used in other devices than magnetrons, for example,klystrons.

Accordingly, it is desired this invention be not limited to theparticular details of the embodiments disclosed herein except as definedby the appended claims.

What is claimed is:

1. An electron discharge device comprising an evacuated envelopeincluding an anode structure and a pair of oppositely disposed magneticpole pieces, said anode structure including a plurality of anodemembers, a cathode spaced from said anode members, tuning meanspositioned adjacent said anode structure, a support member attached tosaid tuning means and movable with respect to said anode structure, anda resilient conducting member consisting of a toroidal springsurrounding said support member and in resilient contact with saidsupport member and one of said pole pieces.

2. An electron discharge device comprising a cathode, an anode spacedfrom said cathode, tuning means positioned adjacent said anode, aplurality of support members attached to said tuning means and movablewith respect to said anode, and a resilient conducting member consistingof a toroidal spring surrounding and in resilient contact with each ofsaid support members.

3. An electron discharge device comprising a cathode, an anode structurespaced from said cathode, means including a pair of oppositely disposedpole pieces attached to said anode for producing a magnetic field in thespace between said anode structure and said cathode in a directionsubstantially transverse to the electron paths,

tuning means positioned adjacent said anode structure, a plurality ofsupport members attached to said tuning means and movable With respectto said anode structure, and a resilient conducting member consisting ofa toroidal spring surrounding each of said support members and inresilient contact with each of said support members and one of said polepieces.

4. An electron discharge device comprising a cathode, an anode spacedfrom said cathode, means for producing a magnetic field in the spacebetween said anode and said cathode in a direction substantiallytransverse to the electron paths, tuning means positioned adjacent saidanode, a plurality of support members attached to said tuning means andmovable with respect to said anode, and a resilient conducting memberconsisting of a toroidal spring surrounding and in resilient contactwith each of said support members, said resilient conducting memberbeing substantially fixed with respect to said anode.

5. A cavity resonator, tuning means for said cavity resonator movablypositioned adjacent said resonator, a support member attached to saidtuning means and movable with respect to said resonator, and a resilientconducting member consisting of a toroidal spring surrounding and inresilient contact with said support member.

References Cited in the file of this patent UNITED STATES PATENTS

